upper limb
Upper Limb Anatomy
outline
Introduction to upper limb
Overview of developmental anatomy
Bones of the upper limb
Joints of upper limb
Muscles of upper limb
Vascular supply and innervation of upperlimb
Interactive
Assignments
Clinical applications
Multiple choice questions
Assignments- osteology of Upperlimb
Characteristics of the various bone of the upper-limb
support
Stability
biomechanics
Surgical considerations of the various bone
Done in ppt by groups
Clavicle
Shape
S-shaped bone
flat laterally, tubular centrally, and prismatic medially
clavicle
Articulations
Sternoclavicular joint
stabilisers
posterior capsular ligament
anterior sternoclavicular ligament
costoclavicular ligament
intra-articular disc
Acromioclavicular joint
stabilisers
coracoclavicular ligament
acromioclavicular ligament
Clavicle- example
Biomechanics
middle third is weakest portion of clavicle (why?)
thinnest and narrowest
transitional area of the bone in both curvature and in cross-sectional anatomy
only area not supported by ligamentous or muscular attachments
Clinical implications- middle 3rd Clavicular fracture commonest
Scapular assignment
“Arm or Brachium”
Humerus assignment
Forearm “antebrachium”
Consists of the
Radius (lateral)
Ulna (medial)
In anatomical position-supinated
Both are connected along their length by a ligament (interosseous membrane)
Forearm regarded as joint because of the pronation supination movements
axis of rotation of forearm runs through radial head (proximal) and ulna fovea (distal)
distal radius effectively rotates around the distal ulna in pronosupination
Ligaments
Interosseous membrane (IOM)
occupies the space between the radius and ulna
permits rotation of the radius around the ulna
NB- radial shaft bowed
head-neck osteology
the radial head is 15º offset from the neck (not collinear)
anterolateral third of radial head lacks subchondral bone
easily fractured in this area
articular surface
has 40º oval-shaped concavity that articulates with capitellum
Biomechanics
radial head confers two types of stability to the elbow
valgus stability
secondary restraint to valgus load at the elbow, important if MCL deficient
longitudinal stability
restraint to proximal migration of the radius
Distal radius
responsible for 80% of axial load
articulates with
scaphoid
via scaphoid fossa
lunate
via lunate fossa
distal ulna
via ulnar/sigmoid notch
ulna
olecranon
together with coronoid process, forms the greater sigmoid (semilunar) notch
greater sigmoid notch articulates with trochlea
provides flexion-extension movement
adds to stability of elbow joint
Coronoid process
coronoid tip
is an intraarticular structure
can be visualized during elbow arthroscopy
medial facet-important for varus stability
provides insertion for the medial ulnar collateral ligament
Coronoid ractures, radial head fractures
Biomechanics
coronoid functions as an anterior buttress of the olecranon greater sigmoid notch
important in preventing recurrent posterior subluxation
primary resistor of elbow subluxation or dislocation
The Hand
Consists of:
Carpals (8) “wrist”
Metacarpals (5) “palm”
Phalanges (14) “fingers”
Review of the Carpals
So Luke Took Peter To The Church Hall
So ----- Scahpoid
Luke -- Lunate
Took -- Triquetrum
Peter - Pisiform
To ----- Trapezium
The --- Trapezoid
Church- Capitate
Hall ---- Hamate
Carpal bones
Eight carpal bones makeup the wrist
How do these bones develop and what are the clinical significance or implications of its development
Embryology of bone
Bone development begins with limb bud formation which forms the blue print for subsequent differentiation of tissues
Limb bud develops within the third week of embryogenesis from the mesenchymal cells of the lateral plate and cells of adjacent somites
Endochondral ossification
By the 6th week of gestation condensation occurs at the sites of bone development
It involves aggregation of mesenchymal cells that outline the shape and size of the future bone
The mesenchymal cells differentiate into either chondrocytes
Chondrocytes form cartilage models which is the basis of endochondral bone formation
Endochondral bone formation
Cartilagenous model of bone is replaced with bone
Epiphyseal morphogenesis and longitudinal bone growth is dependent on endochondral bone formation
Stages of endochondral bone formation
Formation of future bone template by mesenchymal cells
Differentiation of mesenchymal cells into chondrocytes
Development of primary ossification centres
Development of secondary ossification centres
Periosteal development and appositional growth
Mesenchymal template or anlage begins to from at six weeks of gestation
Differentiation of mesenchymal cells into chondrocytes giving a cartilaginous model (type 10 collagen) of the template
At the centre of the cartilaginous model, hypertrophy of chondrocytes occur followed by apoptosis with simultaneous vascularization of the centre
The process brings osteoblast and osteogenic cells to the centre
Producing osteoid (type 1 collagen)at around the 8th week- Primary ossification centre
The capillary buds that lead vascularization of the anlage brings along myeloid/haematopoetic cells
Resorption of central anlage leads to marrow formation
As fetus grows the primary ossification centres expand forming the diaphysis
Chondrocytes continues to proliferate increasing length of the bone
Chondrocytes at the ends of long bones undergo subsequent hypertrophy and apoptosis with vascularisation and invasion with osteoblast to form secondary ossification centre- by birth
this leads to formation epiphyseal centre and growth plate
Cartilage is subsequently found at the ends of articular cartilage
Between the epiphyseal centre and diaphysis
secondary ossification centre-deposits bone which becomes the epiphysis
The epiphyseal centre or growth plate is key for longitudinal growth of long bones.
Two forms of the growth plate exist in immature bone
Horizontal plate (the physis)
Spherical plate proximal to it and less well organised compared to the horizontal
Spatial organization of the horizontal growth plate is as follows from secondary ossification centre to diaphysis
Reserve Zone
Proliferative zone
Hypertrophic zone
Maturation zone
Degenerative zone
Provisional calcification zone
Spatial organisation of growth plate
Reserve Zone
Proliferative zone
Hypertrophic zone
Maturation zone
Degenerative zone
Provisional calcification zone
Characteristics of zones
Reserve zone-
cells store lipids, glycogen, and proteoglycan aggregates; decreased oxygen tension occurs in this zone
proliferative zone
growth is longitudinal, with stacking of chondrocytes (the top cell is the dividing “mother” cell), cellular proliferation, and matrix production
increased oxygen tension and increased proteoglycans inhibit calcification
Hypertrophic zone
Normal matrix mineralization occurs in the lower hypertrophic zone: chondrocytes increase five times in size, accumulate calcium in their mitochondria, die, and release calcium from matrix vesicles.
Metaphysis
Adjacent to the physis and expands with skeletal growth
Primary spongiosa
Vascular invasion and resorption of transverse septa with Bone formation
Secondary spongiosa-Remodeling Internal: removal of cartilage bars, replacement of fiber bone with lamellar bone External: funnelization
Factors influencing growth plate development
Local factors
Work via paracrine pathway derived from platelets, chondrocytes, endothelial cells, cartilage matrix
Etiological basis of pathologies with respect the physis
Etiological basis of pathologies with respect the physis
Examples of the common disorders
rickets
achondroplasia
Gigantism
Appearance of secondary ossification centres- tells the age
elbow
JOINTS
A joint is a region where two or more bones or cartilages unit/articulate.
The skeleton is designed in such a way as to allow a wide range of movement.
These movements occur at the junctions between the apposed bones.
Not all joints, however, are movable.
FUNCTIONAL DESIGN OF THE UPPER LIMB
FOR REACH
FOR PREHENSILE FUNCTION
FOR SKILLED MOVEMENTS
TOUCH, TYPING, PLAYING, PUSHING
FEEDING
FOR POWER GRIP
CLIMBING, PULLING
FOR PROTECTION/AGGRESION
FIGHTING
MOST PROXIMAL JOINT (SHOULDER JOINT)
DESIGNED TO ENABLE REACH TO ALL PARTS OF THE BODY
INTERMEDIATE JOINTS
ELBOW JOINT (MAJOR SEGMENT TO ALLOW FOR FLEXION AND EXTENTION)
RADIO-ULNA JOINTS (TO ALLOW FOR PRONATION AND SUPINATION)
DISTAL JOINTS (RADIO-CARPAL; CARPO-METACARPAL; METACARPO-PHALANGEAL; INTER-PHALANGEAL)
DESIGNED FOR PREHENSILE FUNCTION AND POWER GRIPS
The stability of joints depend on:
the shape, the size and nature of arrangement of the articular surface of the bones,
the ligaments supporting the bones
the tone of muscles around the joint.
[a steady partially contracted state of a muscle caused by the successive flow of nerve impulses.
OR the amount of tension or resistance to movement in a muscle].
Shoulder stability
Static restraints
glenohumeral ligaments (below)
glenoid labrum (below)
articular congruity and version
caspsule
negative intraarticular pressure (if release head will sublux inferiorly)
Static restraints
glenohumeral ligaments (below)
glenoid labrum (below)
articular congruity and version
caspsule
negative intraarticular pressure (if release head will sublux inferiorly
average diameter is 43 mm
approximate retroversion 20° from transepicondylar axis of the distal humerus
articular surface inclined upward 130° from the shaft
Bursa- A fluid filled sac that act as a cushion between moving/ articulating parts of the body eg. Bones, muscles, joints and tendons.
Elbow joint
Joint includes
ulnohumeral joint
radiocapitellar joint
proximal radioulnar joint
joint type
pivot joint - the radiohumeral articulation is a pivot joint
hinge joint - the ulnohumeral articulation is a hinge joint
radial head is covered by cartilage for approximately 240 degrees
the lateral 120 degrees contains no cartilage
this is crucial for internal fixation of radial head fractures
coronoid fossa
coronoid fossa on distal humerus receives the coronoid tip in deeper flexion
coronoid tip
the coronoid tip has a buttress effect in the prevention of posterior dislocations
ulna band of the Lateral collateral ligament (LCL) primary constraint to posterio-lateral rotatory instability
Provides support against varus stress
annular ligament
provides stability to the proximal radioulnar joint
accessory collateral ligament
Lateral elbow stability
Secondary static constraints
Capsule (most stabilizing effect with elbow extended)
Radio-humeral articulation (important secondary constraint to valgus instability)
Common flexor and extensor tendon origins
Dynamic stabilizers
includes muscles crossing elbow joint
anconeus
brachialis
triceps
biceps
they provide compressive stability
Elbow dislocations-image
DRUJ
articulation occurs between the ulnar head and sigmoid notch (a shallow concavity found along ulnar border of distal radius)
most stable in supination
Primary stabilizers
volar and dorsal radioulnar ligaments
Triangular Fibrocartilage Complex (TFCC)TFCC
TFCC attaches to the fovea at the base of the ulnar styloid
components include
central articular disc
meniscal homologue
volar and dorsal radioulnar ligaments
ulnolunate and ulnotriquetral ligament origins
floor of the ECU tendon sheath
muscles
Shoulder girdle
muscles
Shoulder girdle
Shoulder & Pectoral region
Shoulder- Pectoral region
Shoulder & Pectoral region
Shoulder
Deltoid m
Origin-lateral end of the clavicle, acromion and spine of the scapula.
Insertion- deltoid tuberosity of the humerus.
Innervation-Axillary nerve, C5-6.
Action- abduction, Flexion and extension of the arm
Rotator cuff muscles
Includes:
Subscapularis
Supraspinatus
Infraspinatus
Teres minor
QUADRANGULAR SPACE?
TRIANGLE OF AUSCULTATION?
Subscapularis
Origin: From subscapular fossa
Insert: the lesser tubercle of the humerus
-Medial rotation
Nerve-
Upper (superior) and Lower (inferior) subscapular nerves (C5,C6)
It forms the post. Axillary wall
Supraspinatus,
From supraspinous fossa of scapular to upper facet of greater tubercle of the humerus
-initiates abduction of the shoulder
Assist in abducting the arm
Suprascapular N (C5,C6)
Infraspinatus
From infraspinous fossa to middle facet of greater tubercle of humerus
-Powerful lateral rotator of the humerus
Suprascapular N
Teres minor-from the upper 2/3 of the dorsal surface of scapular
Just above the insertion of T. major to lower facet on the greater tuberosity of humerus
Lateral rotation & weak adductor of humerus
Axillary N
arm
The anterior flexor compartment contains three muscles: the coracobrachialis, the biceps brachii, and the brachialis.
Two are flexors of the elbow; all are supplied by the musculocutaneous nerve.
The posterior extensor compartment consists of one muscle, the triceps brachii, which is supplied by the radial nerve.
In the distal two thirds of the arm, the muscle compartments are separated by lateral and medial intermuscular septa
superficial layer
Deep layer
Arm- Anterior Compartment
Flexor compartment
Contains biceps brachii, the coracobrachialis and the brachialis
All innervated by the Musculocutaneous nerve, C5,6,7.
They flex the arm and forearm.
Anterior Compartment
Biceps brachii
Long head attaches to supraglenoid tubercle.
The short head originates from the coracoid process of the scapula.
Inserted into the radial tuberosity and bicipital aponeurosis.
Strongest supinator of the forearm.
A strong flexor of the forearm (when forearm is not supinated).
Coracobrachialis
Origin-
tip of the coracoid process
Insertion-
middle of the medial side of the shaft of humerus.
Nerve supply-Musculocutaneous N.
Flexes the arm, weak adductor of the arm
Brachialis
Origin-Distal, ventral surface of the humerus
Insertion- coronoid process of the ulna.
Innervation-Musculocutaneous (C5-C6)
Action- Flexes the elbow.
Posterior compartment of the arm -Triceps brachii
Origin- Long H from the infraglenoid tubercle, lateral head from the upper part of the posterior surface of the humerus and medial H from the lower part of the posterior surface of the humerus.
Insertion- upper surface of olecranon process of ulna
A powerful extensor of the forearm.
Extends and adducts the arm by way of its long head.
Innervated by the radial N
Carrying Angle of the Elbow
Forearm- flexor group
The flexor-pronator group is arranged in three layers.
In the superficial layer, four muscles arise from the common flexor origin on the medial humeral epicondyle and fan out across the forearm.
They are easy to remember by the following simple maneuver.
Place the butt of the opposite hand over the medial epicondyle, with the palm on the anterior surface of the forearm:
the thumb points in the direction of the pronator teres,
the index finger represents the flexor carpi radialis,
the middle finger represents the palmaris longus,
and the ring finger represents the flexor carpi ulnaris
Surface Anatomy - Anterior Forearm
The middle layer consists of the flexor digitorum superficialis.
The deep layer is comprised of three muscles: the flexor digitorum profundus, the flexor pollicis longus, and the pronator quadratus
Extensor group or dorsal group Twelve muscles appear on the dorsal aspect of the forearm.
They are divided into three groups, as follows
The mobile wad of three (the brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis) runs along the lateral side of the forearm.
These three muscles arise from a continuous line on the lateral supracondylar ridge and lateral epicondyle of the humerus.
four superficial extensor muscles fan out from the lateral epicondyle of the humerus.
From the ulnar to the radial side of the forearm, they consist of the
anconeus,
the extensor carpi ulnaris,
the extensor digiti minimi,
and the extensor digitorum communis
Of the five deep muscles, three (the abductor pollicis longus, the extensor pollicis brevis, and the extensor pollicis longus) supply the thumb.
The three cross the forearm obliquely from the ulnar to the radial side, and two of them (the abductor pollicis longus and the extensor pollicis brevis) wind around the dorsal and lateral aspects of the radius.
The remaining two muscles of the deep group are the supinator and the extensor indicis
Assignment- functions of the various muscles of the forearm
Vascular supply- arm
The vascular organization of the arm is relatively simple; each nerve takes one artery with it.
The brachial artery runs with the median nerve down the medial border of the arm under the biceps brachii muscle and onto the brachialis muscle. The artery can be palpated along its entire length, because the deep fascia of the arm is the only medial covering. The artery lies medial to the humerus in the upper two thirds of the arm. At the elbow, it curves laterally to lie over the anterior surface of the bone, where it may be damaged in supracondylar fractures of the humerus
The profunda brachii artery runs with the radial nerve, supplying the triceps brachii muscle (see Figs. 2-41 and 2-42).
The ulnar collateral artery runs with the ulnar nerve. The three arteries anastomose freely with one another around the elbow joint.
elbow
The brachial artery enters the cubital fossa, running on the lateral side of the median nerve and lying on the brachialis muscle
Halfway down cubital fossa, the artery divides into two terminal branches: the radial and ulnar arteries
The radial artery passes medial to the biceps tendon before turning anteriorly, lying on the supinator muscle and the insertion of the pronator teres muscle. In the upper forearm, it lies under the brachioradialis muscle (see Fig. 4-11).
The ulnar artery usually disappears from the cubital fossa by passing deep to the deep head of the pronator teres, the muscle that separates it from the median nerve
forearm
Innervation- median nerve
Motor
superficial volar forearm group
Pronator teres
Flexor carpi radialis
Palmaris longus
intermediate group
Flexor digitorum superficialis
deep group
Flexor digitorum profundus (lateral)
Flexor pollicis longus
Pronator quadratus
Course of the median nerve
Anterior compartment of arm
anterior compartment (anteromedial to humerus)
runs with brachial artery (lateral in upper arm / medial at elbow)
no branches in the arm
Forearm
enters the forearm between the pronator teres and biceps tendon
travels between flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP)
then emerges between the FDS and flexor pollicis longus (FPL)
Radial nerve
Motor
radial nerve proper
triceps, Aconeus
ECRL, ERCB
Brachioradilais
PIN
ED, Supinator
EDM, ECU
APL, EPL
EPB
EIP
images
Sensory
posterior cutaneous nerve arm
posterior cutaneous nerve - forearm
superficial branch radial nerve
dorsal digital branch
images
Ulna nerve
Motor Innervation
forearm
FCU
FDP ring and small
thenar
adductor pollicis
deep head of flexor pollicis brevis (FPB)
fingers
interossei (dorsal & palmar)
3rd & 4th lumbricals
hypothenar muscles
abductor digiti minimi
opponens digiti minimi
flexor digiti minimi
Sensory Innervation
sensory branches of ulnar nerve
dorsal cutaneous branch
palmar cutaneous branch
superficial terminal branches